In this video, we're going to begin our lesson on the classes of connective tissue. Recall from our previous lesson videos that connective tissue is the most diverse primary type of tissue in terms of both its structures and its functions. Because connective tissues are so diverse, they can actually be grouped in slightly different ways. Different textbooks and different professors can group connective tissues differently. Here in this video, we're going to explain how we've strategically decided to group connective tissues in our lesson. In this lesson, we are going to be grouping connective tissues into 2 major classes that you can see numbered down below, number 1 and number 2.
The first major class of connective tissue in our lesson is going to be connective tissue proper, which is also sometimes referred to as general connective tissue or fibrous connective tissue. The second major class of connective tissue in our lesson is going to be specialized connective tissue. Connective tissue proper, once again, is also sometimes referred to as general connective tissue because these tissues tend to have more generalized functions that are not really specific or limited to any particular body system, area, or process. Instead, these generalized functions tend to be more basic and fundamental, and more widely utilized throughout multiple body systems, areas, and processes. The ground substance of these tissues tends to be gelatinous or more of a semi-fluid, something in between a solid and a liquid.
Connective tissue proper or general connective tissue, once again, is also sometimes referred to as fibrous connective tissue because these tissues tend to be really rich in terms of their protein fibers that are found in their extracellular matrix. These protein fibers often are pretty conspicuous or distinct and easily seen under a light microscope. Connective tissue proper or general connective tissue or fibrous connective tissue, whatever your professor decides to use, is always going to include both loose and dense connective tissues. Moving forward in our course in different videos, we'll be able to talk more about loose connective tissues and dense connective tissues.
The second major class of connective tissues in our lesson is going to be specialized connective tissue. As its name implies with the term specialized, these tissues tend to have more highly specific functions that tend to be more unique to the particular tissue. Those specific functions tend to be more specific or limited to just one or a few body systems. The ground substance of these tissues is either a solid or a liquid rather than being gelatinous. Specialized connective tissue is going to include cartilage, bones, and blood and lymph. As we'll learn moving forward in our course, cartilage and bones do have protein fibers in their extracellular matrix, but they tend to be a little bit harder to see under a light microscope without specialized staining techniques. Blood and lymph don't really have those protein fibers in their extracellular matrix.
If we take a look at our image down below, notice that we're showing you how we are grouping connective tissues in our lesson. Notice that immediately we have connective tissues at the top and we can group them into 2 major classes. Once again, we can group them into connective tissue proper or general connective tissue, or fibrous connective tissue, or we can group them into specialized connective tissue. Recall that connective tissue proper or general or fibrous connective tissue is going to always include both loose and dense connective tissues. The specialized connective tissues include cartilage, bone, and blood and lymph.
As we move forward in our course, we'll be able to talk more details about each of these connective tissues. Notice down below, what we have is a scale or a spectrum of the ground substance viscosity in the extracellular matrix or how thick the ground substance is. On one extreme or one end, what we have is a rock hard solid ground substance. On the other extreme, the other end, what we have is a liquid ground substance. Recall once again that connective tissue proper or general or fibrous connective tissues, which includes loose and dense, they tend to have more of a gelatinous ground substance that is going to be more of a semi-fluid in between a solid and a liquid. You can see here where they lie on the spectrum. With specialized connective tissues, they are either going to have a solid or a liquid ground substance. Both bone and cartilage are going to have more of a solid ground substance and then blood and lymph is going to have more of a liquid ground substance. This here concludes our brief introduction to the classes of connective tissue. As we move forward in our course, we'll be able to talk about each of these connective tissues in their own separate videos in more detail. I'll see you all in our next video.